Scala中的单词计数示例？

Question

我看到很多Scala教程,其中包含一些示例,例如招聘遍历或解决数学问题.在我的日常编程生活中,我感觉我的大部分编码时间都花在了字符串操作,数据库查询和日期操作等普通任务上.有兴趣举例说明以下perl脚本的Scala版本吗？

#!/usr/bin/perl
use strict;
#opens a file with on each line one word and counts the number of occurrences 
# of each word, case insensitive
print "Enter the name of your file, ie myfile.txt:\n";
my $val = <STDIN>;
chomp ($val);
open (HNDL, "$val") || die "wrong filename";

my %count = ();
while ($val = <HNDL>)
{
        chomp($val);
    $count{lc $val}++;
}
close (HNDL);

print "Number of instances found of:\n";
foreach my $word (sort keys %count) {
        print "$word\t: " . $count{$word} . " \n";
}

综上所述:

• 要求提供文件名
• 读取文件(每行包含1个字)
• 消除线端(cr,lf或crlf)
• 小写这个词
• 增加字数
• 打印出每个单词,按字母顺序排序,以及计数

TIA

Answer 1

像这样的简单字数可以写成如下:

import io.Source
import java.io.FileNotFoundException

object WC {

  def main(args: Array[String]) {
    println("Enter the name of your file, ie myfile.txt:")
    val fileName = readLine

    val words = try {
      Source.fromFile(fileName).getLines.toSeq.map(_.toLowerCase.trim)
    } catch {
      case e: FileNotFoundException =>
        sys.error("No file named %s found".format(fileName))
    }

    val counts = words.groupBy(identity).mapValues(_.size)

    println("Number of instances found of:")
    for((word, count) <- counts) println("%s\t%d".format(word, count))

  }

}